(1) Field of the Invention
The present invention relates to waveguide/large core fiber couplers, and more specifically to monolithically integrated waveguide or large core fiber couplers for multi-wavelength, high power, beam combining with increased brightness and/or beam quality.
(2) Description of the Prior Art
U.S. Pat. No. 6,490,388 discloses a side-pumped laser including an optical fiber with a core and a cladding. The core has an index of refraction n1 and the cladding has an index of refraction n2, where n1>n2. The fiber further includes a coupling window integrally formed within a channel formed in an upper side of the fiber cladding. The coupling window consists of an optical material having an index of refraction of n where n3>n1. The fiber laser further includes a laser light source that is directed through the coupling window where laser light is directly coupled into the core of the fiber. The fiber of the laser also preferably includes Bragg gratings written into the core beneath the coupling window and a reflective material disposed in a second window formed beneath the Bragg gratings. The side-pumped fiber laser is located at a distance from the fiber in order to direct light into the coupling window of the fiber. A need still exists to improve coupling efficiency of side pumped laser arrangements.